L 6 a Dermatology

Clinical Foundations of Dermatology and Patient History

Factors in Dermatologic Evaluation: Assessing dermatologic disorders requires a comprehensive approach covering history, lesion types, and distribution patterns. - History Components: - Systemic symptoms (fever, malaise). - Symptomatic nature of lesions (itching, pain, burning). - New exposures (medications, chemicals, plants, environmental changes). - Types of Lesions: - Primary changes: The initial manifestation of the disease (e.g., macules, papules). - Secondary changes: Modifications resulting from external factors such as scratching (excoriation), infection, or healing. - Distribution Patterns: - Isolated Lesions: Nevi (moles), skin cancers (Basal Cell Carcinoma, Squamous Cell Carcinoma, Melanoma), Keratoacanthoma, Molluscum, and Verruca (warts). - Generalized Rashes: Psoriasis, Erythema multiforme, Urticaria (hives), Measles, Pityriasis rosea, and Roseola. - Facial Rashes: Seborrheic dermatitis, Rosacea, Perioral dermatitis, Erythema infectiosum (Fifth disease), and Actinic keratosis. - Hands and Feet: Hand, Foot, and Mouth disease; Secondary syphilis; Erythema multiforme; Tinea (fungal infection); and Dermatitis.
Diagnostic Modalities: The most common diagnostic modality in Primary Care (PCP) dermatology is a combination of thorough History and Physical Examination, leading to a Clinical Diagnosis.
Common Topical Therapeutics in PCP: Cleansers, sunscreens, Emollients, moisturizers, Corticosteroids, Anti-fungals, Antibiotics, Antiparasitics, and Acne medications.

Atopic Dermatitis: Case Study of Sara Scratches

Patient Profile: Sara is a $9\,y/o$ female reporting an "itchy rash on elbows and behind knees."
Subjective History: - Recurrent pruritic (itchy) skin lesions in the popliteal (behind knees) and antecubital (inside elbows) fossae bilaterally. - Condition flares significantly during winter months. - Patient reports dry skin and increased itching/rash severity upon scratching. - Additional History Questions: Assess aggravating/alleviating factors, history of allergies, and specific onset.
Clinical Findings: - Vitals: BP $110/70\,mmHg$ (right arm, sitting); HR $85\,bpm$ ; Temp $98.2\,F$ (oral). - Physical Exam: Round, erythematous (red) patches with confluent papules in bilateral antecubital fossae, accompanied by excoriation (scratch marks).
Differential Diagnoses (DDX): Allergic contact dermatitis, Contact dermatitis, Atopic dermatitis (Eczema), Tinea corporis, Psoriasis, Pityriasis rosea, Seborrheic dermatitis, Lichen simplex chronicus, and Scabies.
Supportive Diagnostic Signs for Atopy: - Family history of atopy (Asthma, Allergies, Atopic Dermatitis). - Hyper-linearity of palms: Increased number of skin lines on the palms. - Dennie-Morgan folds: Also known as an atopic pleat; an extra fold/line under the eyes. - Allergic shiners: Dark circles under the eyes related to congestion. - Hertoghe’s sign: Thinning or loss of the outer (lateral) third of the eyebrows (also seen in hypothyroidism). - Presence of other flexural rashes.

Vehicles and Principles of Topical Therapy

Topical Efficacy Factors: Efficacy depends on the vehicle (carrier), active ingredient concentration, anatomic location of application, and patient acceptability/adherence. - Note on Generics: Generics and brand names may differ in vehicle formulation and may not have equal efficacy.
Types of Vehicles (Driving the Active Ingredient): - Ointment: Suspension emulsion, semisolid, contains < 20\% water. It is translucent, occlusive (traps moisture), greasy, and increases skin hydration and drug penetration. - Cream (Most Common): Emulsion semisolid, contains > 20\% water. It is white, easily spreadable, less greasy than ointment, and less occlusive. - Lotion: Liquid or solution of diluted cream, contains > 50\% water. May contain alcohol ( $OH$ ), providing a cooling and drying effect. - Gel: Semi-solid with a gelling agent for stiffness; greaseless and non-occlusive. - Foam/Aerosol: Agent delivered under pressure; ideal for scalp or hair-bearing areas.
Emollients (Repairing the Barrier): Critical for Atopic Dermatitis (AD) management. - Application: Lukewarm bath/shower for $10-15\,minutes$ , pat dry, and apply product immediately. Daily use is recommended. - Products: Lipid-rich ceramide creams (e.g., CeraVe, Vanicream, Atopiclair) or Petrolatum-based emollients. - Additives: Colloidal oatmeal, oils, liquid paraffin. Bleach baths ( $1/2\,c$ to full bathtub) may be used for bacterial control.

Topical Corticosteroids (TC) and Adjuvant Therapy

Usage Principles: Used to treat flares. Potency choice (Classes I-VII) depends on age, body area, and inflammation severity. - Face and Skin Folds: Use low potency (Class $VI-VII$ ) regardless of severity; high potency should be avoided. Calcineurin inhibitors can be an alternative. - Rule of Thumb: Switch to a different potency class rather than just increasing the percentage of the current drug.
Eczema Severity Categorization (UK Quality of Life): - Mild: Dry skin, infrequent itching, little impact on activities of daily living (ADL). - Moderate: Redness, frequent itching (with/without excoriation), moderate impact on ADL, frequent sleep disturbance. - Severe: Widespread dryness, incessant itching, bleeding, oozing, cracking, or pigment changes; severe ADL limitation and nightly sleep loss.
TC Potency Examples: - Classes I-III (Ultra-high): Clobetasol proprionate $0.05\%$ (Cream/Ointment), Halobetasol proprionate $0.05\%$ , Betamethasone dipropionate $0.05\%$ , Triamcinolone diacetate $0.5\%\,\text{C}$ . - Classes IV-V (Medium): Mometasone furoate $0.1\%\,\text{C/O/L}$ , Triamcinolone acetonide $0.1\%\,\text{O}$ , Fluticasone propionate $0.05\%\,\text{C}$ . - Classes VI-VII (Low): Alclometasone dipropionate $0.05\%\,\text{C/O}$ , Hydrocortisone $0.5-2.5\%\,\text{C/O/L}$ , Fluocinolone acetonide $0.01\%\,\text{C/S}$ .
Side Effects of TC: Skin atrophy, bruising, striae (stretch marks), masking signs of infection (e.g., fungal), and systemic risks like HPA axis suppression, cataracts, or glaucoma.
Non-Steroidal Rescue Agents: - Topical Calcineurin Inhibitors: Tacrolimus, Pimecrolimus. - Topical PDE4 Inhibitors: Crisaborole.
Supplemental Care: Vitamin D supplementation ( $1600\,IU$ ) correlates with improved eczema. Topical probiotics ( $Staph$ ) applied twice daily ( $BID$ ) for $7-30\,days$ may be beneficial. Oral probiotics show mixed results.

Tinea Corporis: Case Study of George Corporal

Patient Profile: George is a $19\,y/o$ male wrestler with a rash on his thigh for $2-3\,weeks$ . It is itchy.
Clinical Findings: - Vitals: BP $115/73\,mmHg$ ; HR $65\,bpm$ ; Temp $97.9\,F$ . - Physical Exam: Annular (ring-shaped), erythematous scaling $2\,cm$ plaque on the medial aspect of the right upper thigh.
Diagnostic Confirmation: - KOH Prep ( $10\%$ potassium hydroxide): Best way to confirm fungal infection. Looking for branching fungal hyphae. - Wood’s Lamp: Some dermatophytes fluoresce under specific light. - Differential Diagnoses: Nummular dermatitis, Tinea versicolor, Psoriasis, Pityriasis rosea, Lyme disease, Secondary syphilis.
Other Lab Tests: Gram stain (bacteria), PCR (Herpes/Spirochetes), Scrapping under oil (Scabies), Culture (Bacterial/Viral), Diascopy (vascular vs non-vascular), Biopsy (chronic eruptions).
Antifungal Therapeutics: - Azoles (Fungistatic): Broad-spectrum; good if yeast vs. fungus is unclear. Includes Clotrimazole (OTC), Miconazole (OTC), Ketoconazole (OTC), Econazole ( $C$ ). - Allylamines (Fungicidal): More effective than azoles with higher cure rates and lower relapse. Includes Terbinafine (OTC $1\%\,\text{cream/solution}$ ), Butenafine, and Naftifine.
Principles of Antifungal Application: - Treat for $2-4\,weeks$ (sometimes $6$ ), continuing for $1\,week$ after the lesion clears. - Apply to the lesion plus a $2\,cm$ margin of normal-appearing skin $1-2$ times daily. - Avoid combination products (e.g., steroid + antifungal).

Acne Vulgaris: Case Study of Paula Pustule

Patient Profile: Paula is a $16\,y/o$ female with painful pimples on cheeks and chin for $2\,weeks$ . Reports oily skin since age $12$ and pre-menstrual flares.
Clinical Findings: - Vitals: BP $114/63\,mmHg$ ; HR $71\,bpm$ ; Temp $98.7\,F$ . - Physical Exam: Open and closed comedones with crusted pustules and erythematous papules on chin and cheeks.
Etiology: Caused by $Cutibacterium\,acnes$ (formerly $Propionibacterium\,acnes$ ).
Classification Guidelines: - Grade I (Comedonal): Whiteheads only, few inflammatory lesions. - Grade II (Papular): $10-25$ papules/pustules, mild inflammation. - Grade III (Pustular): > 25 papules, moderate inflammation. - Grade IV (Severe Papulonodular): Numerous papules, nodules, and cysts. - Severity: - Mild: Limited to face, comedones with few inflammatory lesions. - Moderate: $10-40$ comedones; $10-40$ inflammatory papules/pustules. - Moderately-Severe: $40-100$ comedones; $40-100$ papules/pustules; $5-10$ nodules. Widespread (face, chest, back). - Severe: Extensive nodules and cysts.
Lab Workup (for resistant cases or signs of PCOS): Free and total testosterone, DHEA, LH, FSH, Prolactin, and $9\,am$ cortisol to rule out Congenital Adrenal Hyperplasia ( $CAH$ ).
Management Principles: - Patience: Treatment is preventative; takes $4\,weeks$ to $6\,months$ for full effect. - First Line Therapies: - Mild: Benzoyl Peroxide ( $BPO$ ), topical retinoid, or combination (BPO + antibiotic). - Moderate: Topical combination OR Oral antibiotic + topical retinoid + BPO. - Severe: Oral antibiotic + combination therapy OR Oral isotretinoin.

Acne Medications and Application

Topical Retinoids: Apply at bedtime ( $HS$ ) because sunlight causes degradation. Start "low and go slow" (every $2-3\,days$ ) to mitigate irritation. Use a pea-sized amount for the whole face. - Tretinoin: $0.025\%$ , $0.05\%$ , $0.1\%$ (Cream/Gel). Microsphere versions reduce irritation. - Adapalene: $0.1\%$ , $0.3\%$ . Best tolerated OTC option. - Tazarotene: $0.05\%$ , $0.1\%$ . Most effective but also most irritating. Contraindicated in pregnancy.
Topical Antimicrobials: Used for inflammatory acne. Always use with BPO to prevent resistance. - BPO ( $2.5-10\%$ ): Most effective at $2.5\%$ . Can bleach hair/clothing. - Clindamycin ( $1\%\,\text{G/S/L}$ ) or Erythromycin ( $2\%\,\text{G/S}$ ): Typically applied in the morning ( $AM$ ) while retinoids are applied at night ( $PM$ ).
Combination Products: - Adapalene $0.1\%$ / BPO $2.5\%\,\text{gel}$ . - Clindamycin $1.2\%$ / Tretinoin $0.025\%\,\text{gel}$ . - Clindamycin $1.2\%$ / BPO ( $2.5\%$ or $5\%\,\text{gel}$ ).

Basal Cell Carcinoma (BCC): Case Study of Mary Solarium

Patient Profile: Mary is a $63\,y/o$ female reporting a red, flaky spot on her neck for several months.
Clinical Findings: - Vitals: BP $129/79\,mmHg$ ; HR $83\,bpm$ ; Temp $98.2\,F$ . - Physical Exam: Subtle pink and whitish well-defined $1.3\,cm$ patch with overlying scale on the midline base of the neck. - Dermascopy Findings: Arborizing telangiectasias (sharp bright red branching vessels), shiny white structures, blue-gray dots, and leaf-like areas.
Risk Stratification for BCC: - Low Risk: Superficial or nodular tumors, well-defined, no neural involvement. Small lesions on trunk/extremities (< 2\,cm). - High Risk: Neural involvement, micronodular/infiltrating types, poorly defined borders, tumors > 2\,cm on trunk. Locations in the "Mask area of face" (eyelids, nose, lips, ears, etc.), genitalia, hands, or feet.
Management Options: - Surgery (First Line): Standard excision ( $4\,mm$ margins for low risk), Mohs Micrographic Surgery (MMS), or Electrodessication and Curettage (ED&C). - MMS (Mohs): Preferred for high-risk areas, recurrent tumors, or poorly defined borders to preserve healthy tissue. - Topical Therapy: - Imiquimod: Immune response modifier. Used for superficial BCC on trunk/neck only. Applied daily (Mon-Fri) for $6\,weeks$ . - $5-Fluorouracil\,(5-FU)$ : Anti-metabolite chemotherapy for superficial BCC. Applied $BID$ for $3-6\,weeks$ .

Patient Education and Sun Protection

Skin Exams: Total body skin exams recommended $1-2$ times per year for patients with history of BCC.
Sunscreen Guidelines: - Use SPF $30+$ daily. - Apply $15-30\,minutes$ prior to exposure and reapply every $2\,hours$ . - Quantity Guide for Adults: - Average total dose: $6-9\,tsps$ . - Face and Neck: $1\,tsp$ . - Torso (Front + Back): $2\,tsps$ . - Upper Extremities (UE): $1\,tsp$ ; Lower Extremities (LE): $2\,tsps$ .